This connection has two types: rigid and pin joint:
Pin Joint
• Pin or simple joint is a kind of connection which is designed for bearing vertical load and there isn’t any moment at the intersection of the beam and column. Designing and controlling pin joints of H.S.S is the same as joints in the closed section column with stiffener (made of quadrilateral plate) or open sections (I).
 
simple hss joint
 
stiffener kinds
Rigid Joint
• It is a kind of joints that in addition to resist shearing force of vertical loads, is able to resist the effect of lateral (wind or earthquake) loads too. Therefore these connections which are able to transfer the whole moment capacity of beam-to-column are fully-restrained connections.
 ConXL connection